The patterns of activity in the brains of neonates, though it is critical for the normal development of synaptic connectivity, is largely unknown. Recent work has shown that in the cortex of neonatal rats, nearly all neuronal activity consists of bursts of synchronous oscillatory activity similar to spindle waves observed in adults during sleep. In the somatosensory cortex these bursts are correlated with spontaneous muscle jerks and sensory input. How precisely such correlation comes about will be important to understand how different regions coordinate activity in the time before normal sensory input develops. The visual system is an excellent model in which to study this question. Much of the organization of the visual system occurs before vision, driven by spontaneous bursts of activity in retinal ganglion cells. Through a combination of paired recordings, pharmacological manipulation of the retina, and electrical stimulation, the experiments in this proposal will discern if retinal activity patterns activity in the major visual targets, or if it acts to trigger endogenous oscillators centrally. This information will aid in the development of accurate models of activity dependent development.